Designing an Anaphora Resolution Algorithm for Route Instructions

[in(left_region_of(street1)]). The second rule handles cases in which the spatial PP
specifies the verb but the specification also allows inference about the properties of
the corresponding argument. This happens when the corresponding argument is
realised as anaphor like in the following examples:
3) you will see it on your left
4) it is on your left there
As pronouns cannot be specified by PPs, the spatial PP: ‘on your left’ modifies the
verb. However, it can be inferred through the reasoning processes that the entities
referred to by the anaphors are both located in the left_region of the robot. These
spatial inference rules are especially defined for the domain of route instructions.
The second rule takes Adjective Copula Constructions into account where
the adjective modifies either an abstract entity (e.g. x is true) or a concrete entity (e.g.
x is expensive). Depending on the kind of adjective, it also constrains the subject to be
a certain kind of entity, for example in the following example:
5) follow the road to the museum
6) be careful, it is quite bendy
The lexical entry for ‘bendy’ stores the information that ‘bendy’ is likely to specify
an entity of the concept: ‘path’ (cf. lexical entry for ‘bendy’ in Appendix 3). By virtue
of the constraint (retrievable from the lexicon) the algorithm would not try to resolve
the anaphor to ‘the museum’.
The third rule checks the lexicon for type constraints for the Arguments of
Verbs (subject or object). The lexical entry of each verb contains type constraints for
the subject and if the verb is transitive it also stores type constraints for the object.
The lexical entries for ‘reach’ and ‘take’ show that the subject is restricted to either a
‘human_person’ or a ‘path’. As ‘reach’ belongs to the subclass of REACH-verbs its
object is specified as final position of the action (see lexical entry of ‘reach’ in
Appendix 3). ‘Take’ is a TURN-verb. Therefore, its object is restricted to be a ‘path’-
entity (cf. lexical entry of ‘take’ in Appendix 3). ‘Assume’ is a PROPOSITIONAL
ATTITUDE-verb, which is why its complement is defined as a propositional clause
(cf. lexical entry of ‘assume’ in Appendix 3). The object of ‘do’ always refers to an
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